WILMINGTON, North Carolina -- Climate change may be predicted by fish who "eavesdrop" their way to healthy food sources using chemical cues given off by ocean organisms. This research, conducted by the University of North Carolina Wilmington assistant professor Sean Lema and collaborators, was published in the March edition of the journal Science in the article "Dimethylsulfoniopropionate as a Foraging Cue for Reef Fishes."

Marine animals gather and spawn in the "islands" of productive coral reef habitats. On the Caribbean island of Curacao, Netherlands Antilles, Lema and collaborators Jennifer DeBose and Gabrielle Nevitt from the University of California Davis found that the sulfur compound dimethylsulfoniopropionate (DMSP) can provide odor signals that communicate the presence of healthy food sources for marine organisms.

The research team found that some fish aggregated to releases of DMSP, a byproduct of algae and phytoplankton in reefs, usually indicating algae growth, or that tiny animals in plankton are feeding on the algae.

"Algae is the first level in the ocean food chain. Understanding how marine creatures find such productive hotspots can help us track these populations and their long-term impact on the sea." said Lema, Department of Biology and Marine Biology and Center for Marine Science.

Instead of smelling food directly, the team observed that the fish used the scent to "eavesdrop" to the interaction between plant plankton and their predators. It has been previously suggested that some reef fish use biogenic chemicals as aggregation and foraging cues, but DMSP is the first specific chemical to be identified as serving this role.

"When you see changes in global water conditions, you will see changes in these chemical productions and animals in habitats, and possibly global climate. DMSP byproducts are studied quite often in conjunction with climate change." noted Lema.

Measuring DMSP and related marine fish patterns may help scientists track global climate regulation. When released from the ocean, derivatives of DMSP in the atmosphere promote cloud formation. Clouds reflect sunlight back into space and cool the Earth.

"DMSP may also be a good indicator of the health of coral reef habitats," said Lema.

The research team's findings could aid the conservation of damaged reefs, as stressed or damaged coral can become "bleached when they lose zooxanthellae, one-celled organisms that live inside coral polyps that give off DMSP. In the near future, Lema and his colleagues plan to conduct additional experiments.

Lema said, "We will continue to explore the impact of chemicals like DMSP on species movement. We want to get a better grasp on how these chemicals are produced on reefs and how they vary across the world. This may be nature's way of communicating with us about vital changes we need to make to conserve our environment."

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